The problem with the Cimarron is mainly the trapway, which has not improved since it was introduced.
Class 4,5,6,7 are marketing terms now.
The numbers mean nothing.
In real use, a Toto class 4 is equal to a Eljer class 7
A Eljer class 7 and Toto 4 are better then the Kohler class 5 and 6
All of these use a 3" or larger flush valve.
But you still have to look at the trapway. That is where the clogging occurs.
The Cimarron trapway has too tight of bends where it leaves the bowl.
It does clog more then other trapways out there in real use.
If you look at quality of construction, and consistent rinse, then the Toto class 4 comes out at the top.
Toto doesn't keep changing the number, they are the ones being chased.
4 was meant to be a classification for commercial products.
That's as high as you get.
The other manufacturers can come out with
Newer, bigger, surreal, octofying, suptregasping, amectacking, unreally, wackanobby,
it doesn't change a thing.
My personal experience with Class 6 Cimarron, is that the rinse is now 360, but still not very good.